MODEM.ASM : the origin version of XMODEM implementation.
XMODEM.ASM : an adaption for CP/M.
XMODEM/CRC : Along with 1byte checksum & 2byte CRC-16
XModem-1k : XMODEM/CRC with 1024 byte data
YModem : Refers to the XModem/CRC(optional 1k blocks) protocol with batch transmission.
True YModem: An attempt to sort out the YModem Tower of Babel.
ZModem: Use XModem/CRC & YModem technology in a new protocol .
ZOO:Compress program.